Simple Spring Microscope

This simple single-lens microscope, which is little more than a magnifying lens with a sample holder, was common during the middle of the seventeenth century.

There were a number of variations of the general design scheme for these types of microscopes, and this one uses a simple spring attached to the microscope base as a sample holder. The user would affix a specimen to the sharpened tip of the holder by one of several methods and then use the lens to examine the specimen. Focus was accomplished by squeezing the "spring-loaded" sample holder in and out with respect to the shapely wooden microscope base. This is no doubt the simplest possible form of controlling specimen/lens distance, as the pressure brought on the spring from the hand would allow the microscopist to focus the sample. A device this crude is only useful at very low magnifications where the depth of focus is considerable.